Hydrocarbon wave reformer and methods of use

ABSTRACT

A method and system of using a type of wave rotor to reform a hydrocarbon fluid using pressure waves within the wave rotor to reformulate a hydrocarbon fluid, such as methane or the like, into a lighter hydrocarbon, hydrogen, or, in some instances, hydrogen, partially decomposed hydrocarbon fluid and carbon solids.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/452,807, filed Jan. 31, 2017, and to U.S. Patent Application Ser. No.15/885,453, filed Jan. 31, 2018, U.S. Pat. Pub. No. 2018/0215615,published on Aug. 2, 2018, now U.S. Pat. No. 11,220,428, dated Jan. 11,2022.

TECHNICAL FIELD

The present invention relates to systems and methods for hydrocarbonfluid reforming, hydrogen generation, solid carbon formation and carboncapture. More specifically, this is a new and useful fluid reformerutilizing systems and methods which include wave rotors to promotethermal and/or catalytic decomposition of fluids.

BACKGROUND ART

Carbon Dioxide emissions are believed to be one of the leadingcontributors to global climate changes. As a result, research sectors,industry sectors and public policy sectors are racing to find ways toreduce the carbon footprint of humans, to help reduce, minimize, andeven eliminate the carbon dioxide emissions from energy sources such asfossil fuels.

Hydrogen is one such fuel that is being used more prevalently today as aresult of these attempts to reduce our carbon footprint. Hydrogen gascan be used to produce power with no negative impact on the environment,unlike power produced using fossil fuels.

Hydrogen can be produced using many methods, however the overwhelmingmajority of industrial hydrogen is generated using steam methanereforming. Steam methane reforming is a process where methane and steamare heated until they react, reforming into hydrogen and carbon dioxide.The chemical reaction describing steam reforming of the hydrocarbonmethane is:

CH4+2 H2O+ENERGY=>CO2+4 H2

Steam methane reforming is a well-developed and refined process that hasbecome an industry standard. Notwithstanding, steam reforming has itsdraw backs. Most notably, it generates carbon dioxide which is currentlyvented to the atmosphere. Additionally, the energy required for theprocess is generated using hydrocarbon fuels, further adding to thecarbon dioxide emission problem. A second drawback of the steam methanereforming process is that it consumes water (steam), which is becoming avaluable resource. In addition to the environmental impacts, the capitalcost of steam reforming plants is prohibitive for small to medium sizeapplications because the technology does not scale down well.

Thus, there remains a significant unmet need for providing anenvironmentally friendly, cost effective and scalable hydrogenproduction method. What is needed are better hydrogen production systemsand methods.

SUMMARY OF INVENTION

Methods and systems for employing direct hydrocarbon reforming aredescribed. Direct hydrocarbon reforming requires much less energy thansteam methane reforming and can be configured for cost-effectivehydrogen production that produces no carbon dioxide and consumes nowater. For comparison to steam methane reforming, the chemical equationdescribing direct methane reforming into hydrogen and solid carbon is:

X CH4+ENERGY=>2 H2+C(s)+(X−1)CH4

Compared to steam methane reforming, the energy required for directmethane reforming is less, no carbon dioxide is generated, no water isconsumed and the carbon, which forms into a solid form is readilycollected and can be a secondary product. Direct hydrocarbon reformingcan solve many unmet needs in hydrogen production.

Methods for employing a wave rotor for hydrocarbon fluid reforming areprovided. Some of the methods include providing a fluid supply to theinput of a wave rotor having an inlet and an outlet, heating thehydrocarbon fluid using pressure waves in one or more stages,decomposing the hydrocarbon fluid as a result of the heating. In someembodiments the reforming process further includes separating thereformed fluid from the working fluid, holding the reformed fluid at acertain state, and/or separating the reformed fluid into its solid andfluid constituents.

Systems employing a wave rotor for hydrocarbon reforming are alsoprovided. Exemplary systems include, at least, a pressurized hydrocarbonfluid, a wave rotor, a fluid solid separator, and a means for collectingthe reformed fluid.

The hydrocarbon wave reformer has unique properties including those thatallow for continuous, efficient and scalable hydrocarbon thermaldecomposition with or without a catalyst. The wave reformer is a “coldwall” reformer where the energy for heating and reforming the workingfluid comes from a pressure-driven energy exchange process onboard therotor. This is a benefit of the wave reformer over current directhydrocarbon reforming methods because there is nothing in the reformerto foul, allowing for continuous operation. Additional benefits overcurrent reformers are lower energy consumption and better scalability.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B provide representations of inventive wave reformers.

FIG. 1A is an exemplary embodiment of a wave reformer that is a pressuredriven wave reformer which uses a wave rotor to reform a supplied fluidusing a high pressure working fluid, causing compression heating of thesupplied fluid on onboard the wave rotor.

FIG. 1B is an exemplary embodiment of a wave reformer which uses energyrelease or phase change to provide compression heating to the suppliedfluid on board the rotor.

FIGS. 2A through 2C provides representations of closed loop systems.

FIG. 2A is an exemplary embodiment of a closed loop wave reformer systemwhich includes a fluid supply being supplied to one wave reformer inflowport of the wave reformer.

FIG. 2B represents a different embodiment of the closed loop systemwhich further includes a heater and/or a fan/compressor for addingadditional energy to the working fluid in the reforming process.

FIG. 2C is a schematic for a closed loop wave reformer system.

FIG. 2D is a chart of data measured at state points for a closed loopwave reformer system

FIGS. 3A and 3B provide representations of open loop wave reformingsystems.

FIG. 3A shows a fluid supply directed to an inflow port of a wavereformer.

FIG. 3B provides alternative embodiments of a closed loop system whichoptionally includes one or more heaters to add energy to the system, orat least one settling chamber.

FIG. 3C is a schematic of an open loop wave reforming system embodiment.

FIG. 3D is a chart of data measured at state points for an open loopwave reforming system.

FIG. 4 provides a typical wave cycle for a compression-driven heatingcycle that is known in the wave heating art.

FIG. 5 provides at least one illustration of a wave rotor known in thefuel heating art.

DESCRIPTION OF EMBODIMENTS

Wave rotors provide a unique solution to the hydrocarbon reformingindustry. A wave rotor designed to reform hydrocarbon fluids (gases andliquids) into primarily hydrogen and solid carbon as well as lesseramounts of lighter hydrocarbons is described. The wave reformer usespressure waves to heat and reform a fluid onboard a rotor. Thus, thesystems described provide a continuous scalable system which requireslittle outside energy input to produce a reformed gas. The systems andmethods further provide a secondary benefit of solid carbon production.Finally, the systems and methods described do not create additional CO2gas that needs to be captured and/or sequestered as a result of thereforming process nor do they consume any water.

The following detailed description is merely exemplary in nature and isin no way intended to limit the scope of the invention, its application,or uses, which may vary. The invention is described with relation to thenon-limiting definitions and terminology included herein. Thesedefinitions and terminology are not designed to function as a limitationon the scope or practice of the invention, but are presented forillustrative and descriptive purposes only.

Various terms used throughout the specification and claims are definedas set forth below as it may be helpful to an understanding of thesystems and methods described.

As used herein “fluid” shall mean any liquid, gas, or plasma orcombination of phases that has the ability to flow. A “fluid” may alsocontain some amount of solid or particulate mixed within the liquid,gas, or plasma or combination of phases.

As used herein a “wave rotor” shall mean a device that exchanges energyonboard a rotor using pressure waves. Wave rotors can be of variousdesigns including for example, axial or radial design. The pressurewaves onboard the rotor can be generated by port openings and closingsas well as combustion and/or phase change onboard the rotor. Wave rotorsare further described in Kielb, R., Castrogiovanni, A. and Voland, R.,“Wave Rotors for Continuous, Vitiate-Free, High-Enthalpy Test GasGeneration”, JANNAF APS, December, 2014, which is incorporated herein byreference.

As used herein a “wave reformer” is a system utilizing a wave rotor forreforming a hydrocarbon fluid. As used herein, the term “hydrogen fluid”shall be understood to mean decomposed fluid constituents which containhydrogen.

As used herein “fluid constituents” shall mean decomposed fluids,un-decomposed fluids, hydrogen fluid, suspended solids, and mixtures orcombinations thereof.

As used herein “hydrocarbon” shall mean any compound or natural gasconsisting entirely of, or substantially of, hydrogen and carbon bondedmolecules. In addition, a hydrocarbon may alternatively include anymixture of fluids that include any amount of molecules containinghydrogen and carbon bonded atoms which may be mixed with other fluids ormolecules whether or not such other fluids and molecules contain anycarbon bonded molecules.

As used herein “working fluid” shall refer to any fluid onboard therotor which goes through a compression or expansion process.

As used herein “reformed fluid” shall refer to the fluid which has beenconverted, cracked or reformed into lighter constituents than theoriginal fluid.

Systems and methods for wave reforming a hydrocarbon fluid using a waverotor are described.

It is to be understood that in instances where a range of values areprovided that the range is intended to encompass not only the end pointvalues of the range but also intermediate values of the range asexplicitly being included within the range and varying by the lastsignificant figure of the range. By way of example, a recited range offrom 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

System

A system for providing hydrocarbon fluid reforming is provided. Thesystem includes at least a high pressure hydrocarbon supply, at leastone wave rotor having at least one inlet port and at least one outletport, and a separator for separating the reformed fluid exhausted fromthe outlet port into its solid and fluid constituents.

It is appreciated that many hydrocarbon fluids are known in the art.Without intending to limit the invention, a hydrocarbon fluid mayinclude for example, methane, ethane, propane, butane, pentane, hexane,heptane, octane, nonane, docane, or any alkane, alkene, alkyne,cycloakane, alkadiene, or other variations related thereto.

The wave rotor may be an axial or radial type wave rotor. Additionally,the wave rotor can be designed to input energy to the flow(wave-compressor), extract energy from the flow (wave-turbine) or tominimize the shaft power required (wave-rotor). It is appreciated thatthe wave rotor may move at various speeds. In some embodiments the waverotor rotates within a range of 10 to 30,000 RPM.

In at least one embodiment a settling chamber is used as an output fromthe wave rotor. The settling chamber is intended to increase the time ofthe fluid at high temperature to promote additional thermaldecomposition of the reformed hydrocarbon fluid.

It is appreciated that many heat losses are produced in the system, thusin at least some embodiments, one or more heaters or heat exchangers maybe used to maximize thermal decomposition. In some embodiments, one ormore regenerative heat exchangers are used to reuse heat generated bythe system for pre-heating or re-heating hydrocarbon fluids in thesystem. In some embodiments, a heater using additional energy from anexternal source is employed to re-add heat losses to the system. It isappreciated that heat is lost through thermal expansion of a compressedfluid. It is further appreciated that heat is generated as a result offluid compressions, either as a result of the wave rotor, or anycompressor which may be employed in or with the system. An exemplary useof a regenerative heat exchanger is to pre-heat incoming hydrocarbonfluids to be reformed with outgoing reformed fluids. In an alternativeexemplary use, regenerative heat exchangers are employed for reheatingfluids between stages or cycles of the wave rotor.

Some embodiments may optionally include one or more compressors to bothincrease the system pressure of a fluid, and to add additional heatlosses to the system. In at least one embodiment, a portion ofhydrocarbon supply exhausting from at least one outlet port of said waverotor is supplied to a second inlet port of the wave rotor to be driven(or heated) by the expansion of the incoming hydrocarbon fluid supply inthe first stage of the wave rotor.

In some embodiments, the system optionally includes one or more controlheaters. As discussed previously these heaters may be regenerative heatexchangers or heaters powered from an external energy source. In suchembodiments, a pre-heater is optionally used for pre-heating thecompressed hydrocarbon supply (the driven fluid) prior to supplying tothe second inlet port of the wave rotor.

In some embodiments, a method for introducing reaction catalyst to thehydrocarbon fluid prior to supplying the said fluid to the wave rotor isincluded.

In some embodiments, a solid carbon transport system is employed fortransporting the separated carbon as a result of the reforming processfrom the separator to.

In some embodiments, a catalytic carbon separator for assisting in theseparation and processing of the transported solid carbon is provided.

FIGS. 1A and 1B are representations of inventive wave reformers. FIG. 1Aprovides for one embodiment of a wave reformer that is a pressure drivenwave reformer which uses a wave rotor to reform a supplied fluid using ahigh pressure working fluid, causing compression heating of the suppliedfluid on onboard the wave rotor. FIG. 1B provides for another embodimentof a wave reformer which uses energy release or phase change to providecompression heating to the supplied fluid on board the rotor.

FIGS. 2A-2B provides representations of closed loop systems. FIG. 2Aprovides at least one embodiment of a closed loop wave reformer systemwhich includes a 100 fluid supply being supplied to one 31 wave reformerinflow port of the 30 wave reformer. In this embodiment, the workingfluid is exhausted from at least one 33 wave reformer outflow port. Theworking fluid exhausted from the 34 outflow port is redirected back toanother 32 wave reformer inflow port where it is converted from aworking fluid to a reformed fluid on board the rotor, and eventuallyexhausted as a reformed fluid from the 33 outflow port. FIG. 2Brepresents a different embodiment of the closed loop system whichfurther includes a 40 heater and/or a 50 fan/compressor for addingadditional energy to the working fluid in the reforming process. FIG. 2Bfurther illustrates a 20 pre-heater to the 100 incoming fluid supply tothe 30 wave reformer and an optional 60 settling chamber. It isappreciated that some or all of the additional components may be addedto the system of FIG. 2A depending on the use and specifications of thedesired system.

FIGS. 3A-3B provides representations of open loop wave reformingsystems. FIG. 3A provides that a 100, 70 fluid supply be directed to aninflow port 31, 32 of a wave reformer 30. Either of the 100, 70 may be aworking fluid and a driven fluid. After reforming the working fluid thedriven fluid and the reformed fluid are exhausted from the 33, 34outflow ports from the 30 wave reformer. The Driver fluid is exhaustedto atmosphere or may be reprocessed as preferred, while the driven fluidis reformed on board the rotor and exhausted. FIG. 3B providesalternative embodiments of a closed loop system which optional includesone or more 20, 40 heaters to add energy to the system, or at least one60 settling chamber to increase the time of the fluid at hightemperature to promote additional thermal decomposition of the reformedfluid. It is appreciated that some or all of the additional componentsmay be added to the system of FIG. 3A depending on the use andspecifications of the desired system.

FIG. 4 provides a typical wave cycle for a compression-driven heatingcycle that is known in the wave heating art. The driver gas, driven gas,test gas and exhaust gas are depicted. The schematic representationshows pressure waves.

FIG. 5 provides at least one illustration of a wave rotor known in thegas heating art. Wave rotors are a class of devices that use pressurewaves to exchange energy between one or more fluids onboard the rotor.FIG. 5 illustrates a wave rotor 80, having a hub 81, a tip-shroud 82,and a series of vanes 83 that connect the hub and tip-shroud, 81 and 82,respectively, to form a series of passages or channels 84 within therotor. Stationary end plates 85 and 86, having ports 87 and 88, and 89and 90 are located adjacent to the rotor at either end. As the rotorturns, the ends of the channels are either exposed to a port or theend-plate wall. As such, the end-plate/rotor combination operate like aset of fast-acting valves permitting fluid flow when a channel isexposed to the port (open) versus when a channel is exposed to the port(closed). Flow (indicated by arrows) and pressure in ports provideboundary conditions that can be used to create useful wave cycles, suchas a fluid heating cycle, onboard the wave rotor 80. The creation anduse of pressure waves onboard a wave rotor 30, such as that described inFIG. 5, are known methods of heating a fuel, such as a hydrogen gas, toobtain hydrogen gas at a much higher temperature (heater). The waverotor 80 of FIG. 5 rotates around rotor axis 91 at a speed set by anexternal electric motor (not shown).

Examples

It is to be understood that while the invention has been described inconjunction with the detailed description thereof, the foregoingdescription is intended to illustrate and not limit the scope of theinvention, which is defined by the scope of the appended claims. Otheraspects, advantages, and modifications are within the scope of thefollowing claims.

Examples Closed Loop

A closed-loop system for providing hydrocarbon fluid reforming isprovided as illustrated in FIG. 2A. In one example, the 100 fluid to bereformed is methane and is brought from a 100 fluid supply beingsupplied to one 31 wave reformer inflow port of the 30 wave reformer.The working fluid is exhausted from at least one 34 wave reformeroutflow port. The working fluid exhausted from the 34 outflow port isredirected back to another 32 wave reformer inflow port where it isconverted from a working fluid to a reformed fluid on board the rotor,and it is eventually exhausted as a reformed fluid from the 33 outflowport.

The flow from the 33 outflow port is optionally directed into a 60settling chamber to maintain the hydrocarbon fluid at the hightemperatures to improve the thermal decomposition of the hydrocarbon gasand further complete the reforming process. Upon completion of thedesired reforming process, the flow is directed to the separation stagewhere the gaseous, solid and optionally liquid states are separated fordownstream processing or use.

FIG. 2B is an example of a closed-loop system with additional componentsthan the example of FIG. 2A.

FIG. 2C is a schematic of another more specific example of closed-loopwave rotor hydrocarbon forming system and method. The closed-loop systemof FIG. 2C is an example of the system integration for Natural GasDecarbonization (NGD). The purpose of NGD is to remove carbon fromNatural Gas (NG), which is generally at least 95% methane (CH4). Forthat reason, the system below assumes the working fluid enters as 100%methane. The system outlined removes 90% of the carbon. The percentageof carbon removed is a design choice.

The system model described below is based on the FIG. 2C schematic. Themodel includes all the components inside the dashed box, which is thecontrol volume for the model. The schematic shows the mass flows thatcross the control volume boundaries at states 0 (fuel inflow), 8(carbon-lean fuel outflow) and 10 (carbon black outflow). What is notshown crossing the control volume in the schematic is the energy inputrequired to drive the Low-Pressure Compressor (LPC), High-PressureCompressor (HPC), Control Heater (CH), Carbon Transport (CT) and WaveReformer (WR). The power required for each component is determined aspart of the system modeling.

The system model revolves around determining the thermodynamic state ofthe fluid at each of the indicated state points, 0 through 12. Toaccomplish this task, it is necessary to assume the performance of eachcomponent. Additionally, the working fluid is simplified from naturalgas, which is about 95% methane, to 100% methane. This was done forsimplicity as the model was developed. The use of the REFPROP packageallows for conversion to a representative natural gas mixture withlittle to no other model changes. A complete list of model assumptionsis presented below:

-   -   The model assumes a 24-hour day    -   The incoming fuel stream is 100% methane    -   The methane decomposes, or cracks, into only hydrogen and solid        carbon    -   The compression processes use 90% isentropic efficiency    -   The heat exchangers have a gas 5% pressure drop and a thermal        efficiency of 90%    -   The mixing and splitting junctions have a 3% pressure drop and        are adiabatic    -   The solid particle separation process has a 15% pressure drop on        the gas side    -   The solid particles exit the separator at atmospheric pressure    -   The fuel supply is delivered at 31 bar (450 psia) and 273 K (59°        F.)    -   The NIST REFPROP v9.1 property package is used for fluid        properties    -   The NASA Chemical Equilibrium with Application (CEA) equilibrium        chemistry model to determine thermal cracking

As shown in FIG. 2C, the fuel inflow (state 0) is routed to a pre-heaterwhere it picks up heat from the high-temperature carbon lean fuel. Thepre-heated fuel (state 1) is mixed with recirculated fuel (state 12)from the high-pressure recirculation loop, the resulting flow (state 2)is routed into the wave reformer high-pressure duct. This flow isexpanded on-board the wave reformer and then routed to the wave reformerlow-pressure exhaust duct, which feeds both recirculation loops. Thereis no reformed or high-temperature fuel routed to the recirculationloop, so carbon build up is not anticipated at either recirculationloop.

The low-pressure recirculation loop is heated to a predeterminedtemperature and routed to the low-pressure inlet duct of the wavereformer. This is the fuel that will be reformed on-board the wavereformer. This fuel is then routed out the wave reformer high-pressureexhaust duct which feeds the solid/gas separator. The flow from theseparator is then delivered to its end use location. An overview of eachof the state points on the schematic is given in Table 1 below.

TABLE 1 SWR System Flow Diagram State Point Description # DescriptionNotes 0 Methane (Natural Gas) Supply 1 Pre-Heated Methane The methane ispreheated using the heat content in the hot gas cracked products 2 HighPressure Wave This stream is a mixture of the incoming and ReformerInflow recirculated fuel. The high-pressure stream drives the processonboard the wave reformer 3 Low Pressure Wave This stream is the expandehigh-pressure Reformer Outflow flow from Port 2. It is split into twoseparate recirculation streams, 4 and 11. 4 Low Pressure This stream isthe inflow to the low-pressure Compressor Inflow recirculation loop. TheLPC is designed to handle the low-pressure recirculation flow 5 ControlHeater Inflow This stream is the inflow to the control heater, which isincluded in the low-pressure recirculation loop. The control heater setsthe temperature of the fuel to be reformed to the appropriate value asit enters the wave reformer. 6 Low Pressure Wave This stream is the lowpressure warm fuel to Reformer Inflow be reformed onboard the wavereformer 7 High Pressure Wave This stream is the high-pressure high-Reformer Outflow temperature reformed fuel which is routed to the solidcarbon separator 8 Reformed Gas Outflow This stream is the reformed gasstream exiting the separator, thus the solids have been separated out.It is the carbon lean fuel that will be delivered to the end user 9Solid Carbon Outflow This stream is the solid carbon stream exiting theseparator. This stream is feed the solid carbon transport system 10Solid Carbon Delivery to Conveyor belt transport to storage or Storagedelivery 11 High Pressure High-pressure recirculation loop required toCompressor Inflow provide required mass flow to set up a periodic wavepattern for the reforming process 12 High Pressure HPC pressure ratiosize to match fuel inflow Recirculation to Wave pressure Reformer

A summary stream table is presented in FIG. 2D, the stream numberscorrespond to the locations shown on the FIG. 2C schematic. Inparticular, FIG. 2D shows mole fraction, total flow, temperature,pressure, density, enthalpy, and entropy for each closed loop statepoint 0 through 12.

Examples Open Loop

An open-loop system for providing hydrocarbon fluid reforming isillustrated in FIG. 3A. In this example, there are two different workingfluids, a driver fluid and a driven fluid. The driver fluid is routedfrom a 70 pressurized supply into the 31 inflow port of the 30 wavereformer. The driver fluid, which expands onboard the rotor, exits therotor through a port 34 and can then be routed to a downstream processor vented to the atmosphere.

The driven fluid, which is the hydrocarbon fluid to be reformed, isbrought in from a 100 pressurized supply. The driven fluid enters thewave reformer through inflow port 32. This fluid is then compressed andheated onboard the rotor prior to exiting the rotor through the outflowport 33. The reformed fluid, is routed for downstream processing thatdepends on the desired final product.

FIG. 3B is an alternative embodiment of a closed loop system whichincludes three optional or additional components, a first heater 20, asecond heater 40 to add energy to the system, and/or at least one 60settling chamber to increase the time of the fluid at high temperatureto promote additional thermal decomposition of the reformed fluid.

FIG. 3C is a more specific embodiment of an open loop hydrocarbon fluidreformer using a wave reformer. Specifically, a schematic of anopen-loop wave reformer system for pressurized natural gas is shown FIG.3C. The system model described here is based on this schematic. Themodel includes all the components inside the dashed box, which is thecontrol volume for the model. The schematic shows the mass flows thatcross the control volume boundaries at states 0 (fuel inflow), 4(lower-pressure natural gas), 8 (carbon-lean fuel outflow) and 10(carbon black outflow). It also shows electric power crossing thecontrol volume. this is the energy input required to drive theLow-Pressure Compressor (LPC), Carbon Transport (CT) and Wave Reformer(WR). The power required for each component is determined as part of thesystem modeling.

The system model calculates the thermodynamic state of the fluid at eachof the indicated state points, 0 through 10. To accomplish this task, itis necessary to assume the performance of each component. Additionally,the working fluid is simplified from natural gas, which is about 95%methane, to 100% methane. This was done for simplicity as the model wasdeveloped. The use of the REFPROP package allows for conversion to arepresentative natural gas mixture with little to no other modelchanges. A complete list of model assumptions is presented below:

-   -   The model assumes a 24-hour day    -   The incoming fuel stream is 100% methane    -   The methane decomposes, or cracks, into only hydrogen and solid        carbon    -   The compression processes use 90% isentropic efficiency    -   The heat exchangers have a gas 5% pressure drop and a thermal        efficiency of 90%    -   The mixing and splitting junctions have a 3% pressure drop and        are adiabatic    -   The solid particle separation process has a 15% pressure drop on        the gas side    -   The solid particles exit the separator at atmospheric pressure    -   The fuel supply is delivered at 31 bar (450 psia) and 273 K (59°        F.)    -   The NIST REFPROP v9.1 property package is used for fluid        properties    -   The NASA Chemical Equilibrium with Application (CEA) equilibrium        chemistry model to determine thermal cracking

As shown in FIG. 3C, the fuel inflow (state 0) is routed to aregenerator where it picks up heat from the high-temperature carbon leanfuel. The partially heated fuel (state 1) is further heated by thepre-heater which is fueled using the carbon lean fuel. The pre-heatedflow (state 2) is routed to the wave reformer high-pressure duct. Thisflow is expanded on-board the wave reformer and routed to the wavereformer low-pressure exhaust ducts, one which feeds the recirculationloop (state 3) and one which is routed back to the primary system at alower pressure (state 4). There is no reformed or high-temperature fuelrouted to the recirculation loop, so carbon build up is not anticipated.

The recirculation loop is heated to a predetermined temperature androuted to the low-pressure inlet duct of the wave reformer (state 6).This is the fuel that will be reformed on-board the wave reformer. Thisfuel is then routed out the wave reformer high-pressure exhaust duct(state 7) which feeds the solid/gas separator. The flow from theseparator is then delivered to its end use location. An overview of eachof the state points on the schematic is given in Table 2 below.

TABLE 2 SWR System Flow Diagram State Point Description # DescriptionNotes 0 Methane (Natural Gas) Supply 1 Methane Pre-Heat A The methane ispreheated using the heat content in the hot gas cracked products 2Methane Pre-Heat B The methane is further preheated using thecarbon-lean fuel for energy 3 Low Pressure Re- circulation Loop Outflow4 Low Pressure Exhaust 5 Control Heater Inflow This stream is the inflowto the control heater, which is included in the low- pressurerecirculation loop. The control heater sets the temperature of the fuelto be reformed to the appropriate value as it enters the wave reformer.6 Low Pressure Wave This stream is the low pressure warm fuel ReformerInflow to be reformed onboard the wave reformer 7 High Pressure WaveThis stream is the high-pressure high- Reformer Outflow temperaturereformed fuel which is routed to the solid carbon separator 8 ReformedGas Outflow This stream is the reformed gas stream exiting theseparator, thus the solids have been separated out. It is the carbonlean fuel that will be delivered to the end user 9 Solid Carbon OutflowThis stream is the solid carbon stream exiting the separator. Thisstream is feed the solid carbon transport system 10 Solid CarbonDelivery to Conveyor belt transport to storage or Storage delivery

A summary stream table is presented in FIG. 3D, the stream numberscorrespond to the locations shown on the schematic and defined in thetable above. Data is presented for each state point 1 through 10 of theopen loop system.

Other Examples

An example of a reformer system with less parts is illustrated in

FIG. 1. The system shown is a three-port wave reformer with at least oneinlet port, 31, 32, and at least one outlet port, 33, 34. The 31, 32,inlet port is fed by a pressurized fluid source with a working fluidthat may, or may not, release energy onboard the rotor. The workingfluid then undergoes a process onboard the rotor where the fluid issplit into two flows, a higher energy stream and a lower energy streamand exhausted from at least one outlet port, 33, 34. The location andsize of each of these inlet and outlet ports may be changed in systemdesign.

Other Embodiments

Referring to FIG. 5, wave rotors have been used in connection with usingpressure waves to heat fluids such as hydrogen. A pressure wave reformeris a type of wave rotor that, in accordance with the embodimentsdescribed, can reform heavy hydrocarbon fluids into lighter hydrocarbonfluids, including hydrogen and solid carbon. In some embodiments thehydrocarbon fluid to be reformed is methane gas. That methane gassourced from fluid supply 100 in FIG. 2B is brought into the pressurewave reformer 30 via wave reformer inflow port 31. The fluid beingintroduced may or may not have a catalyst, such as carbon-based solids,iron-based catalysts, or nickel-based catalysts, included to aid thereforming process and it may be passed through a pre-heater 20 beforebeing fed into the wave reformer 30.

In one demonstration of an embodiment, the methane supplied topre-heater 20 is at roughly 288° K and 3.1 MPa. The methane gas leavesthat pre-heater at roughly 700° K and 2.9 MPa, entering the pressurewave reformer 30 at that pressure and temperature. The methane gasenters flow channels (not shown but represented by the channels 84 ofthe wave rotor of FIG. 5) formed in the pressure wave rotor 30.

A second fluid source is also supplied to the pressure wave reformer 30in some embodiments. That second fluid can be a different fluid, such asan argon gas, or the same hydrocarbon fluid, or in some embodiments,methane gas. In embodiment that use a second fluid source, that secondfluid source may be a fluid, taken from the pressure wave reformer 30via outflow port 34, and recirculated. In one demonstration of anembodiment, the fluid taken from outflow port 34 was partly decomposedmethane (some portion of which is hydrogen) and unreformed methane andother possible hydrocarbons. Depending on the operating temperature andpressure ranges utilized, some of this recirculated fluid can be acarbon-rich partially decomposed hydrocarbon. The recirculated fluid maybe a gas or some combination of gas and liquid and carbon.

In one embodiment, the recirculated fluid leaves the outflow port 34 atabout 384° K and 0.3 MPa. In this embodiment, the recirculated fluid,can be re-heated and compressed by recirculation heater 40 andfan/compressor 50 and reintroduced into the pressure wave reformer viainflow port 32. In one demonstration of this embodiment, therecirculated fluid re-enters the pressure wave reformer at roughly 700°K and 0.349 MPa.

The two fluids are carried onboard the reformer for the period of timerequired for the reforming process. The introduction into the wavereformer of two fluids at different pressures causes shock waves withinthe pressure wave reformer 30. Pressure waves are formed by varying thepressure at the ends of the channels using the ports, or closing off theends of the channels using the walls of the end-plates as the rotorrotates. Shock waves form inside the wave reformer 30. It is theseresulting shock waves that cause expansion and compression waves withinthe reformer that significantly increase fluid temperatures and drivethe reformation process. The reformed fluid is extracted from thepressure wave reformer 30 via outflow port 33 and collected or gathered.

Reforming of the driven hydrocarbon occurs when the temperature/pressurein the reforming region reach sufficient levels to change the molecularstructure of the hydrocarbon fluid. In one demonstration of anembodiment of the invention, this fluid exits the wave reformer 30 atroughly 1094° K and 1.0 MPa. Depending on the objective, the fluidleaving the pressure wave reformer 30 through port 33 may be a lighterhydrocarbon, partially unreformulated hydrocarbon, a carbon-richhydrocarbon or, in the case of one embodiment, hydrogen fluid combinedwith a carbon solid, including for example, carbon black, or othercarbon-rich product such as carbon nanotubes or nanodiamonds. As shownin FIG. 2B, the fluid exiting through port 33 can be routed to asettling chamber 60 to facilitate further decomposition and separationof any particulate from the decomposed fluid. The carbon by-productscreated may be collected/harvested and sold.

In some embodiments, the pressure source is a mechanically pressurizedsource, from a combustion, from phase change process onboard the rotor,or some combination of these. Additionally, the wave reformer can bedesigned to input energy to the flow (wave-compressor), extract energyfrom the flow (wave-turbine) or to minimize the shaft power required(wave-rotor). Because the pressure waves occurring onboard the wavereformer are doing the work, the energy necessary to drive the wavereformer of the present invention is reduced or minimized. The channels,formed by the vanes within the rotor (which are for example, straight,curved or other shapes), run the entire axial length of the rotor.

The generation of the carbon by-products of the exemplary processescreates a secondary revenue stream for the system owner andsignificantly increases the system return on investment. This is indirect contrast to capturing carbon dioxide and then paying to compressand/or sequester that waste gas such as in steam methane reforming. Thepressure wave reformer of the exemplary embodiments is for example anaxial or radial type wave rotor. The wave reformer of some embodimentsis 6 inches in diameter and about 18 inches long for a flow rate on theorder of 0.5 lb/s. The wave rotor itself is scalable, with flow rates onthe order of 1000 lb/s or higher using a wave rotor on the order of 42inches long and 48 inches in diameter.

The hydrocarbon wave reformer has unique properties that facilitatecontinuous, efficient and scalable hydrocarbon thermal decompositionwith or without a catalyst. The wave reformer is a “cold wall” reformerwhere (part or all of) the energy for heating comes from the supplypressure of the fluid being used to drive the process, which, in a someembodiments, can be the fluid being reformed. Because the fluids beingreformed flow through the reformer, the reformer itself does notoverheat (hence the “cold wall” designation). In some embodiments, thesupply pressure, which is generally throttled to a low operatingpressure, is not leveraged as in conventional reforming operations, andcontributes to the wave reformer's superior overall efficiency overthose methods.

While exemplary embodiments have been presented in the foregoingdetailed description, it should be appreciated that a vast number ofvariations exist. It should also be appreciated that the exemplaryembodiments are only examples, and are not intended to limit the scope,applicability, or configuration of the described embodiments in any way.Rather, the foregoing detailed description will provide those skilled inthe art with a convenient road map for implementing the exemplaryembodiments. It should be understood that various changes can be made inthe function and arrangement of elements and method steps withoutdeparting from the scope as set forth in the appended claims and thelegal equivalents thereof.

I claim:
 1. A method of employing a wave rotor to reform a hydrocarbonfluid by decomposing that hydrocarbon fluid into a hydrogen fluid andsolid particulate, the method comprising the steps of: providing a waverotor having one or more fluid inlet ports and one or more fluid outletports; introducing a supply of hydrocarbon fluid at a first pressure tosaid wave rotor through at least one of said one or more fluid inletports; introducing a supply of a pressurized fluid at a pressuredifferent than said hydrocarbon fluid supply first pressure throughanother one of said one or more fluid inlet ports; creating and usingpressure waves in one or more stages of compression or expansion tocrack some or all of the hydrocarbon fluid supplied within said waverotor into said hydrogen fluid and solid particulates; and exhaustingthe hydrogen fluid and any partially reformed hydrocarbon fluid fromsaid wave reformer through at least one of said one or more fluid outletports.
 2. The method of claim 1 wherein the pressure waves being createdare shock waves.
 3. The method of claim 1 further comprising directingthe hydrogen fluid, along with any partially reformed hydrocarbon fluid,from said at least one of said one or more outlet ports into a settlingchamber.
 4. The method of claim 3 wherein said settling chamberthermally and/or catalytically further decomposes any said partiallyreformed hydrocarbon fluid.
 5. The method of claim 1 further comprisingdirecting the hydrogen fluid, along with any partially reformedhydrocarbon fluid, from said at least one of said one or more outletports into a solid carbon separator.
 6. The method of claim 1 furthercomprising directing the hydrogen fluid, along with any partiallyreformed hydrocarbon fluid, from said at least one of said one or moreoutlet ports into a catalytic carbon separator.
 7. The method of claim 1further comprising the step of including a catalyst in said supply ofhydrocarbon fluid being introduced at a first pressure through said atleast one of said fluid inlet ports
 8. The method of claim 1 wherein thecatalyst includes at least one of a carbon-based solid, an iron-basedcatalyst, or a nickel-based catalyst.
 9. The method of claim 1 whereinsaid supply of hydrocarbon fluid being introduced at a first pressurethrough said at least one of said fluid inlet ports is free of anycatalyst.
 10. The method of claim 1 further comprising the step ofproviding a heat exchanger to heat the supply of hydrocarbon fluid priorto being introduced to said wave reformer.
 11. A system for reforming ahydrocarbon fluid into a hydrogen fluid and a solid particulate, thesystem comprising: a rotating wave rotor having a plurality of waverotor channels; a hydrocarbon fluid source of hydrocarbon fluid at afirst pressure; said rotating wave rotor having at least one wave rotorinlet port connected to said hydrocarbon fluid source at a firstpressure and sequentially aligning with said plurality of wave rotorchannels as said rotor rotates about a wave rotor axis permitting flowof hydrocarbon fluid into said plurality of wave rotor channels; a waverotor outlet having at least one outlet port connected to andsequentially aligning with said plurality of wave rotor channels as saidrotor rotates about said wave rotor axis permitting flow of hydrogenfluid and solid particulate out of said wave rotor channels; and asupply of a driver fluid at a second pressure, said second pressurebeing different that than said first pressure, said driver fluid passingthrough said at least one wave rotor inlet port to enter at least one ofsaid plurality of wave rotor channels containing said hydrocarbon fluidat said first pressure, wherein a pressure difference between saidhydrocarbon fluid and said driver fluid within said wave rotor channelcreates pressure waves in one or more stages of compression or expansionto reform some or all of the hydrocarbon fluid supplied within saidrotating wave rotor into said hydrogen fluid and solid particulates. 12.The system of claim 10 wherein the wave rotor is an axial or radialrotor.
 13. A method for employing a wave reformer for decomposing ahydrocarbon fluid, the method comprising: providing a wave reformerhaving at least one inlet and at least one outlet; introducing at leastone hydrocarbon fluid to be decomposed to said wave reformer throughsaid at least one inlet; and creating and using shock waves in one ormore stages of compression or expansion to reform some or all of thehydrocarbon fluid supplied within said wave reformer into hydrogen fluidand solid particulates.